Re: [Xen-devel] [PATCH 0/4] ARM: add PSCI host support

[Andre Przywara <andre.przywara@xxxxxxxxxx>]

On 11/26/2013 12:05 PM, Ian Campbell wrote:
> On Mon, 2013-11-25 at 13:02 +0100, Andre Przywara wrote:
> > Xen did not make use of the host provided ARM PSCI (Power State
> > Coordination Interface) functionality so far, but relied on platform
> > specific SMP bringup functions.
> > This series adds support for PSCI on the host by reading the required
> > information from the DTB and invoking the appropriate handler when
> > bringing up each single CPU.
> > Since PSCI is defined for both ARM32 and ARM64, I put the code in a
> > file shared by both.
> > The ARM32 code was tested on Midway, but the ARM64 code was compile
> > tested only.
> >
> > This approach seems to be the least intrusive, but one could also use
> > more of the current ARM64 code by copying the PSCI/spin-table
> > distinction code to a shared file and use that from both
> > architectures. However that seems more complicated.
Ian,

thanks for the review and for the willingness to take the patches for 
4.4 still. Will address the comments ASAP.
> I don't think that is needed (since armv7 spintable vs armv8 spintable
> mechanisms are a bit different). But I would like to see the psci code
> in a separate psci.c. It's not much code right now but it will likely
> grow.
But there is already a xen/arch/arm/psci.c file, which holds the two 
functions to bring up/take down vCPUs. Not much in here, I could easily 
add my code there, but the scope of those two is quite different and I 
would find it strange to have both host and guest PSCI functions in one 
file.
That was one reason to not create a new file, the other was that I found 
smpboot.c an obvious place to keep functions for SMP bringup in.
So should I use psci_host.c? Or keep it in smpboot.c (at least for the 
time being)?
And beside that there is quite some other (only guest related) code in 
Xen which simply uses *psci* in identifiers and filenames (like 
asm/psci.h), that's why I used the psci_host prefix to tell them apart.
Regards,
Andre.

> I'll comment a bit more on the individual patches shortly.
>
> Thanks.
>
> Ian.
> > Please take a look and complain ;-)
> >
> > Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
> >
> > Andre Przywara (4):
> >    arm: parse PSCI node from the host device-tree
> >    arm: add a function to invoke the PSCI handler and use it
> >    arm: dont give up on EAGAIN if PSCI is defined
> >    arm64: defer CPU initialization on ARM64 if PSCI is present
> >
> >   xen/arch/arm/arm32/smpboot.c |  1 -
> >   xen/arch/arm/arm64/smpboot.c |  7 +++-
> >   xen/arch/arm/smpboot.c       | 89 +++++++++++++++++++++++++++++++++++++++++---
> >   3 files changed, 88 insertions(+), 9 deletions(-)

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